A device for distributing sludge, which is used particularly in applications for building tunnels, is shown in German Patent No. 35 06 463. Several delivery pipes are adapted for connection by their unattached ends to the filler openings of a tunnel. The filler openings are staggered in both the circumferential direction as well as in the direction of the tunnel axis, and are capable of being pressurized one after the other with concrete. The ports of the delivery pipes face the pump, and are mounted by flanges on a distributor plate symmetrically with respect to the axis of rotation of the plate.
A swivel-mounted preferably S-shaped manifold is also provided, having a port which faces the concrete pump and is coupled by a rotating joint, which is coaxial with the axis of symmetry, to a feed-pipe connecting piece (or short feed pipe), leading to the pump, and including a second port, which is mounted by a flange to a connecting piece. The connecting piece is in turn mounted on a rotating plate, and extends through the rotating plate to the distributor plate. The rotating plate is rotatable about the axis of the feed-pipe connecting piece, relative to the stationary distributor plate, so that the connecting piece can be connected to the various ports of the delivery pipes.
The monitoring of the correlation between the position of the connecting piece and the desired delivery-pipe port is accomplished by means of an end-of-cam switch, or by means of an electrical proximity switch. It has been shown, however, that this measure alone is not enough to achieve an exact correlation. The friction between the rotating plate and the distributor plate varies depending on the application time and the wear that the device is subject to. Because of the variations in wear, material settles into wear zones. As a result, the friction characteristics existing at the various ports change, so that further rotation can cause the ports to become either overrun or underrun.
If the feed-through openings are not in exact or true alignment, an increased resistance to flow or even clogging can occur. When steel fiber concrete is pumped, another problem which can occur is that when the rotating plate is turned, a certain amount of steel fibers can become carried with the plate. The steel fibers settle in the rotation crack and build up layers of more or less important thicknesses therein. As a result, gaps develop, and the delivered concrete can bleed through the gaps. Due to the resulting loss in liquid, clogging can occur which, accordingly, can affect the operativeness of the device. This is particularly a problem when there is a free clearance space between the distributor plate and the rotating plate which, in turn, gradually becomes filled with emerging concrete. After the concrete hardens, the clearance space becomes clogged and, as a result, rotation of the plate is no longer possible.
It is an object of the present invention, therefore, to improve known devices of the type described above, for example, so that independent of the consistency of the viscous material to be delivered, and independent of the friction characteristics changing during operation, it is possible to exactly position the rotating plate relative to the distributor plate in the specified flow-through positions.